Power venter for gas fired appliances



Oct. 1, 1968 F. o. SUFFRON ET AL 3,403,952

POWER VENTER FOR GAS FIRED APPLIANCES Filed Feb. 28, 1967 Emit 4 dl VEZ 541 a 60/ /80 a ma M fZAZCH/(fi INVENTORS.

United States Patent POWER VENTER FOR GAS FIRED APPLIANCES Fay 0. Sulfron, Los Angeles, and Elwood M. Fairchild,

North Hollywood, Calif., assignors to American Metal Products Corp., Los Angeles, Calif., a corporation of California Filed Feb. 28, 1967, Ser. No. 619,460 4 Claims. (Cl. 431-20) ABSTRACT OF THE DISCLOSURE The invention is a power vent system for use with gas fired appliances normally equipped with a draft hood. A power driven blower is installed in the vent or stack. The power venter provides updraft from the appliance similar in magnitude as would be provided by gravity flow. Particular controls are provided for the motor driven power venter and the gas valve or the like that controls the supply of energy to the appliance. The power venter operates whenever temperatures in the vent reach a predetermined point. If the power venter fails the energy source to the appliance is interrupted. The energy source is interrupted in the event of a stoppage of air flow such as resulting from a blocked flue. The control means insures that the power venter will continue to operate in the event that a gas valve or the like fails to close in response to the thermostat. After the thermostat has been satisfied the power venter continues to operate sufficiently to purge the products of combustion from the appliance and the vent.

Summary of the invention The invention is a power vent system for gas fired appliances which is intended to overcome deficiencies in gravity venting, as well as to permit discharge of products of combustion from gas fired equipment under conditions which are not conductive to gravity disposal of such products. The power vent system of the invention is intended to be installed on existing gas fired appliances and will not alter the performance of the appliances. Such gas fired appliances are conventially provided with a draft hood.

The exhaust blower which forms the power venter is installed on the downstream side of the existing draft hood and is so sized as to provide an updraft from the appliance similar in magnitude as would be provided by gravity fiow. The updraft provided by the power venter is within the range of updraft under which the appliance has been tested under American Standard requirements.

In the light of the foregoing, objects of the invention include realization of the intents and purposes set forth above.

Certain safety control features are integrally built into the power venter to insure that power venting will be available when the appliance is operating. These safety features as described in detail hereinafter are arranged so that the power venter will be actuated when the appliance thermostat calls for appliance operation or on the other hand that the power venter will be actuated when temperatures in the vent reach a predetermined value. The safety controls further are arranged to provide that the energy source to the appliances, for example, the gas control valve, will be interrupted if the power venter for any reason fails to operate. Further, the safety controls are set up to provide that the energy source to the appliance will be interrupted in the case of blocked flue or vent. Further, the safety controls provide that the power venter will continue to operate in the vent that a gas valve, for example, fails to close in response to a thermostat. After the energy source to the appliances has 3,403,962. Patented Oct. 1, 1968 been shut off, the power venter will continue to operate for a time sufiiciently long to purge the products of combustion from the appliance and the vent. Further objects of the invention reside in the provision of these particular safety control features and the realization of their particular purposes in the system.

Further objects of the invention reside in the specific means and arrangements as described hereinafter for realizing the above purposes.

The power vent system of the invention has certain characteristics and advantages, the realization of which constitute objects of the invention. These include that the system makes possible the use of a vent pipe of substantially smaller size which therefore effects an economy in the pipe itself andealso in the floor and ceiling area through which the pipe passes. Furthermore, the vent pipe can be made of reduced height. It can pass out through the side of a building and terminate there rather than having to be extended to a point above the roof as in gravity systems.

Specification The invention relates to an improvement in the opera.- tion of heating appliances, particularly gas fired appliances, particularly gas fired appliances. The invention is directed primarily to the problem of venting such appliances. For example, in a multistory building, if a boiler is installed in a basement, vent pipe or stack has to be run upwardly through all the floors to the atmosphere. From the economic standpoint, if the size of the vent pipe can be reduced, a distinct advantage has been gained. The herein invention accomplishes this purpose by the combination of a power draft blower with a draft hood. The volume of discharged products is the same, but they are now forced through a smaller conduit.

A draft hood is a device built into the appliance or made a part of the vent pipe or stack, which is designed and constructed to insure the ready escape of the products of combustion in the event of no back draft or stoppage beyond the draft hood; to prevent a back draft from entering the appliance; and neutralizing the elfect of stack action of the chimney or gas vent upon the operation of the appliance. A draft hood is designed to have certain performance characteristics relative to the heating appliance that it is used with. The exhaust blower of the herein invention used with the hood does not produce conditions beyond the protection given to the appliance by the draft hood. If the blower were used with the appliance without the draft hood, it would afiect the combustion in the appliance by providing too much draft or not enough draft.

With the aid of the power venter products of combustion can be discharged to atmosphere at any position relative to the appliance whereas, if a difference in density between hot products of combustion and cooler ambient atmosphere are the sole source of energy the position of discharge will of necessity be higher since in a gravity vent system the greater the vertical distance between the vent discharge and the discharge of the appliance, the greater will be the force to discharge products. This invention produces these forces by means of an electrically driven blower. The draft hood and exhaust blower will not alfect the combustion. The arrangement will overcome wind forces tending to disturb combustion. Positive draft is provided for under all conditions. The design of the draft hood is not changed; it remains the same design originally approved as an integral part of the appliance.

FIGURE 1 is a diagrammatic view of a gas fired appliance equipped with the combination of the invention;

FIGURE 2 is a detail sectional view of the exhaust blower showing the arrangement of the thermostatic controls; and

FIGURE 3 shows simplified circuit diagrams of the control system.

Referring now more in detail to FIGURE 1 of the drawings, numeral designates a gas fired appliance forming a part of a conventional system. The showing is exemplary of systems of this type. The gas burner is supplied with fuel through its line 12 having an electrically operated gas valve 14 in it supplying gas to burner 15. The unit 10 has an outlet conduit 16 for gases of combustion which leads from the draft hood 20 which may be of conventional construction. This unit is a housing or enclosure which the conduit 16 connects to. It has an opening as shown at 22, exposing the interior of the draft hood 20 to atmospheric conditions. The draft hood is at the outlet of appliance 10 for the exhaust gasses. The nature and purposes of a draft hood have been set forth in the foregoing.

The exhaust stack is indicated at 26. Numeral 28 designates a power driven exhaust blower driven by a motor 29. It draws gases from within the hood 20 and exhausts them through the stack 26.

FIGURE 2 shows the exhaust blower and driving motor in more detail, as well as the positioning of certain control elements relative to the blower. The blower it self may be of conventional type comprising a blower housing 32 of generally cylindrical construction having a tangential outlet 34. Within the housing is provided a blower element which may be of the squirrel-cage type as designated at 36. The driving motor 29 is positioned adjacent to the housing 32 and may be attached to it by a circular mounting member or bracket 33 as shown. The motor shaft is connected to the blower unit 36. The housing of the motor 38 has vent openings as shown at 42 and 43 so that air will be drawn in to the housing and over the shaft and bearings 44 and 45 of the motor for cooling them. Between the member 33 and the blower housing 32 is an orifice 46. The rotation of the blower impeller will create a pressure at orifice 46 which will be negative to atmosphere and will therefore draw cooler atmospheric air through the motor and past the motor coils and bearings.

Numeral 54 designates a thermostatic element which may preferably be of the snap-disc type which operates electrical contacts with a snap action at predetermined temperatures. This thermostatic element is preferably placed adjacent to an orifice 60 in the side wall of the blower inlet at a position where there is normally a negative pressure when the blower is operating. Thus, normally, there is a flow of air inwardly through the orifice over the thermostatic element 54. This thermostat may be set to operate at a predetermined temperature, as will be explained more in detail hereinafter. It controls the fuel flow to the gas fired appliance, that is, it controls the gas valve. See FIGURE 3.-In the event of blower failure or stoppage of forced draft, the flow of air through orifice 60 will reverse. Instead of air flowing inwardly over the element 54, hot gases will flow outwardly causing contacts to open and shut down the system.

Numeral 62 designates another similar thermostatic element associated with the side wall of the blower housing 32, as shown. This thermostat is of a similar type except that it will act to close the electrical circuit to the venter in case the normal circuit to the venter fails to cause the venter to operate when the energy supply valve is opened.

FIGURE 3 shows circuit diagrams illustrating the preferred arrangement of controls. The system may be powered, for example, by a 115 volt line. The gas valve 14 is controlled by the thermostat 54. The thermostatic control 62 controls blower 28 as described above. These controls may of course be incorporated into a complete integrated control system including a space thermostat as well as other controls.

Thus, as will be seen, that in the event of excessive vent temperature, the element 62 will start the blower 28 irrespective of operation of the heating appliance. In the event of blower failure, as described above, the thermostatic element 54 will close the gas valve 14.

From the foregoing, those skilled in the art will observe the manner in which the invention achieves and realizes the objects and advantages as set forth in the foregoing, as well as the many additional advantages that are apparent from the detailed description.

The combination of the exhaust blower with the draft hood brings about the many advantageous results set forth in the foregoing. The particular arrangement of the controls makes possible the use of simplified elements, and assures that in the event of excessive heat, the exhaust blower will operate and further in the event of failure of the blower, the system will be shut down.

The foregoing disclosure is representative of a preferred form of the invention and is to be interpreted in an illustrativ rather than a limiting sense, the invention to be accorded the full scope of the claims appended hereto.

What is claimed is:

1. In a system of the character described, in combination, a heating appliance having a stack and equipped with a draft hood, having a vent to atmosphere, an exhaust blower associated with the draft hood for providing force draft therefrom to the stack, the stack having a size in relation to the exhaust blower such that the draft characteristics are substantially the same as they would be with a stack of conventional size without an exhaust blower, and means responsive to the temperature at said exhaust blower for causing said blower to operate at temperatures exceeding a predetermined value.

2. In a system of the character described, in combination, a heating appliance having a stack and equipped with a draft hood, having a vent to atmosphere, an exhaust blower associated with the draft hood for providing forced draft therefrom to the said stack, the stack having a size .in relation to the exhaust blower such that the draft characteristics are substantially the same as they would 'be with a stack of conventional size without an exhaust blower, means controlling the heating appliance and control means responsive to failure of gas flow at said blower for shutting off said heating appliance, and means responsive to the temperature at said exhaust blower for causing said blower to operate at temperatures exceeding a predetermined value.

3. In a system of the character described, in combination, a heating appliance having a stack and equipped with a draft hood, having a vent to atmosphere, an exhaust blower associated with the draft hood for providing force draft therefrom to the said stack, the stack having a size in relation to the exhaust blower such that the draft characteristics are substantially the same as they would be with a stack of conventional size without an exhaust blower, means controlling the heating appliance, control means responsive to failure of gas flow at said blower for shutting off said heating appliance, said control means comprising a temperature responsive means positioned adjacent an orifice located in the inlet to the said exhaust blower where there is normally a negative pressure causing air to flow inwardly through the orifice over the temperature responsive means, so that in the event of positive pressure within the blower housing such as might occur in the event of failure of blower operation, the flow of gases over the temperature responsive means reverses causing it to operate to shut off the heating appliance, and means responsive to the temperature at such exhaust blower for causing said blower to operate at temperatures exceeding a predetermined value.

4. In a system of the character described, in combination, a heating appliance having a stack and an exhaust blower, the exhaust blower being located at a position between the heating appliance and the stack, control means including temperature responsive means positioned adjacent an orifice located in the inlet to the exhaust blower at a position wherein there is normally a negative pressure causing air to flow inwardly over the temperature responsive means so that in the event of positive pressure within the blower such as might result from failure of blower operation, the flow of gases over the temperature responsive means reverses causing it to operate to shut off the heating appliance, and temperature responsive means responsive to temperature at the exhaust blower for causing said blower to operate at temperatures exceeding a predetermined value.

References Cited UNITED STATES PATENTS Struble 126-299 Sharpe 126--299 Matcovieh 158-1 Goodridge 110-162 Van Almelo 158-1 Jenn et a1. 126--21 10 FREDERICK L. MATTESON, JR., Primary Examiner.

E. G. FAVORS, Assistant Examiner. 

